fix: guard updateCache() for uncached blocks and re-cache on restore from trash

Author: Ashutoshx7

js/activity.js

@@ -4266,6 +4266,19 @@ class Activity {
                 const blk = this.blocks.dragGroup[b];
                 this.blocks.blockList[blk].trash = false;
                 this.blocks.moveBlockRelative(blk, dx, dy);
+
+                // Re-cache the container if it was uncached to save
+                // memory in sendStackToTrash().
+                const block = this.blocks.blockList[blk];
+                if (block.container && !block.container.bitmapCache) {
+                    block.container.cache(
+                        0,
+                        0,
+                        Math.max(block.width, 1),
+                        Math.max(block.height, 1)
+                    );
+                }
+
                 this.blocks.blockList[blk].show();
             }
 

js/block.js

@@ -399,6 +399,13 @@ class Block {
     updateCache() {
         const that = this;
         return new Promise((resolve, reject) => {
+            // If the container has no active bitmap cache (e.g., trashed
+            // blocks whose cache was freed), skip the update silently.
+            if (that.container && !that.container.bitmapCache) {
+                resolve();
+                return;
+            }
+
             let loopCount = 0;
             const MAX_RETRIES = 15;
             const INITIAL_DELAY = 100;